Field of the Invention
The field relates generally to media feed systems for an imaging device, and, in particular, to devices for separating feed roll pairs to assist with media jam removal.
Description of the Related Art
Imaging devices such as electrophotographic printers employ a plurality of pairs of parallel rollers to feed and move media. The rollers may be constructed of rubber, rubber coated metal, metal, plastic or combinations of these materials. In each pair, one of the rollers, usually the drive roller, has a fixed position in the frame of the device while the mating roller, usually termed an idler roll or a backup roll, generally has a spring or spring device applying defined amount of force to it to press the two rolls together in an interference type position as opposed to the two rolls being tangential. The drive and backup rolls form between them a linear area of rotary friction which is generally known as a “feed nip” or “nip” into which a media sheet is fed and that is used to move the media sheet along a media path in a controlled manner.
During operation, the media sheet sometimes becomes jammed within the media path and must be removed by the user. The difficulty of the media removal process depends on the accessibility of the jam area and the degree to which the media has become trapped within the media transport system. In prior art designs, the user was required to either pull the media sheet through the feed nip overcoming the forces of the drive mechanism and springs or attempt to remove the trapped media by exploring through the available openings, sometimes resulting in the media sheet being torn and only partially removed. Some imaging device embodiments contain a user activated mechanism for separating drive and backup rolls and freeing the jammed media sheet for easier removal. Successful use of this manual release mechanism depends on the user knowing it is there, knowing how to activate it and finally remembering to release the mechanism to close the feed nip in order for printing to continue. Another drawback with some prior art feed nip release mechanisms is that should the release mechanism break, operation of the feed roll pair may be hampered or prevented due to the malfunction of the release mechanism.
It would be advantageous for a user to automatically be able to open the feed nip to clear a media jam and then automatically close the feed nip without the use of a manually operated separator mechanism. It would be further advantageous to allow for automatic opening of the feed nip without the need for additional motors, door tethers or complicated release features. It would be still further advantageous that the separators be operable to reopen the nip should they be accidentally returned to their closed position without the need to manually reposition them.